Negative-pressure-type booster device

Abstract

A check valve of this negative pressure-type booster device is provided with: a cylindrical section that is integrally formed with a shell disposed on one side, communicates with a connection pipe, and is formed in a cylindrical shape protruding toward the inside of a housing; and a valve body section that is disposed inside the cylindrical section, and is axially fitted, within the cylindrical section, to the cylindrical section such that air is permitted to flow from a negative pressure chamber to the connection pipe while the air is prohibited from flowing from the connection pipe to the negative pressure chamber.

The invention claimed is: 
     
       1. A negative-pressure-type booster device comprising:
 a housing having a first shell and a second shell, the first shell formed integrally with a negative pressure leading portion disposed to cylindrically protrude toward the outside of the housing; 
 a connection pipe fitted to the negative pressure leading portion and connected to a negative pressure source; 
 a movable partition partitioning an internal space in the housing into a negative pressure chamber on one side and a variable pressure chamber on the other side; 
 a valve body retractably assembled to the housing and connected to the movable partition in the housing; 
 an air valve disposed in a shaft hole formed in the valve body, capable of being retractable along an axial direction of the shaft hole with respect to the valve body, and moving integrally with an input shaft member; 
 a negative pressure valve communicating or cutting-off the negative pressure chamber and the variable pressure chamber with each other or from each other in accordance with moving of the air valve with respect to the valve body; 
 an atmospheric valve communicating or cutting-off the negative pressure chamber and atmosphere with each other or from each other in accordance with moving of the air valve with respect to the valve body; and 
 a check valve connecting the connection pipe and the negative pressure chamber to each other, 
 wherein 
 the check valve includes a cylindrical portion formed integrally with the first shell, communicating with the connection pipe, and disposed to cylindrically protrude toward the inside of the housing, and a valve body portion disposed in the cylindrical portion and axially fitted on the cylindrical portion in the cylindrical portion such that air is allowed to be circulated from the negative pressure chamber to the connection pipe and prohibited from circulating from the connection pipe to the negative pressure chamber, and 
 the cylindrical portion, the first shell and the negative pressure leading portion are formed as a monolithic structure. 
 
     
     
       2. The negative-pressure-type booster device according to  claim 1 , wherein the valve body portion includes:
 a valve seat member having a communication path communicating the connection pipe with the negative pressure chamber, and a valve seat surface; 
 a valve body member capable of moving in an axial direction with respect to the valve seat member, cutting off the communication path in a state in which the valve body member is in contact with the valve seat surface, and opening the communication path in a state in which the valve body member is separated from the valve seat surface; and 
 a seal member which is brought into contact with and presses an entire circumference of an inner peripheral surface of the cylindrical portion and is brought into contact with and presses an entire circumference of an outer peripheral surface of the valve seat member so as to seal a space between the cylindrical portion and the valve seat member. 
 
     
     
       3. The negative-pressure-type booster device according to  claim 2 , wherein the seal member includes a curved portion which 1) is integrally formed with the valve body member and 2) has a communication hole, and a contact portion which 1) is formed integrally with the curved portion and 2) is in contact with the entire circumference of the inner circumferential surface of the cylindrical portion to press the cylindrical portion. 
     
     
       4. The negative-pressure-type booster device according to  claim 3 , wherein the valve body member and the seal member comprise, in combination, a film valve. 
     
     
       5. The negative-pressure-type booster device according to  claim 2 , wherein the valve body member and the seal member comprise, in combination, a film valve. 
     
     
       6. The negative-pressure-type booster device according to  claim 1 , wherein an inner diameter of an opening of the cylindrical portion opened toward the negative pressure chamber side is larger than an inner diameter of an opening of the negative pressure leading portion opened toward the negative pressure chamber side.